Ergolytic is the opposite of ergogenic. It is derived from the Greek word ergon, meaning "work" and -lytic, which is the adjective form of the Greek word lysos, meaning "loosing, dissolving, or dissolution." The term ergolytic is used to refer to an agent, device, or factor that impairs athletic performance rather than enhances it. This impairment can be the result of physiological or psychological factors. Some common ergolytic agents are alcohol, tobacco (including smokeless), and marijuana.

Creatinine: (C4H7ON3) The nitrogenous waste product of phosphocreatine metabolism. It is a normal constituent of urine and blood. About .02 g/kg of body-weight of creatinine is excreted by the kidneys each day. Creatinine production is proportional to muscle mass and fairly consistent over time. Those who engage in vigorous exercise and those with higher muscle mass may have more creatinine appear in the urine. Increased quantities of creatinine are found in the urine during advanced stages of renal (kidney) disease.

Creatine (C4H9O2N3) is a colorless, crystalline, nitrogenous organic acid contained in various animal organs and body fluids. Creatine combines with phosphate to form phosphocreatine (creatine phosphate or PCr) which is used in the phosphagen system to form adenosine triphosphate (ATP) which can only be stored in very small amounts.

Athletes are expected to consider multiple factors when making informed decision about nutritional supplement use. Besides rules, regulations and potential health hazards, the efficacy of different nutritional supplements in performance enhancement is a key issue. The aim of this paper was to find evidence for informed decision making by investigating the relationship between specific performance-related reasons for supplement use and the reported use of nutritional supplements.

Supplement use by athletes is complex and research supports the alarming notion of misinformed decisions regarding supplements.

A frequent divergence between the type of supplements chosen by athletes and the rationale dictating the supplement use is hypothesized. Thus, a potentially dangerous incongruence may exist between rationale and practice.